Spain’s new phone number system designed to help consumers identify unwanted sales calls has come under scrutiny after a reported scam involving the 400 prefix emerged just days after its introduction.
The measure came into force on Saturday, October 17, requiring businesses to use numbers beginning with 400 for commercial calls. However, the first reported case of fraud has raised questions about whether the change will do enough to protect people from telephone scammers.
According to Spanish newspaper La Razón, a resident of Puente Genil, Córdoba, reported receiving a suspicious call from someone claiming to work for energy company Iberdrola.
The incident has highlighted a major weakness in the new system: recognising a commercial call does not necessarily mean being able to identify a scam.
Why Spain’s new 400 prefix is facing criticism
The Government introduced the new numbering system to make it easier for people to distinguish sales calls from other telephone communications, allowing them to decide whether to answer.
However, the prefix does not guarantee that the person calling is genuine. Fraudsters can exploit the appearance of legitimacy surrounding the new numbers to persuade unsuspecting consumers to reveal sensitive information.
The reported incident involved a technique known as vishing, in which criminals impersonate trusted organisations over the phone to obtain personal details, banking information or security codes.
The case was reported just days after the new rules took effect, prompting renewed warnings about the limits of relying on a caller’s number to determine whether a conversation is safe.
What should consumers do about suspicious calls?
Spain’s Ministry for Digital Transformation says the new rules form part of a wider campaign against telephone and SMS fraud. The authorities have previously reported blocking more than 400 million fraudulent calls and nearly 32 million fraudulent text messages through the national anti-scam plan.
Under the new arrangements, 400 numbers are designed for outgoing commercial calls only, meaning consumers cannot call them back. Businesses must use the designated numbering for covered sales calls, while customer service communications follow separate rules.
Consumers are advised not to share passwords, verification codes or banking details during unexpected calls, even when the caller appears to represent a familiar company.
If a call raises suspicions, the safest option is to hang up and contact the business using the telephone number listed on its official website, app or paperwork.
Anyone who has already disclosed banking information should contact their bank immediately to protect their account and check for potentially fraudulent transactions.
The new prefix may help identify commercial calls, but it is not a guarantee against fraud. Consumers still need to verify who is contacting them before trusting what they hear.